Spurious mode suppression in bulk acoustic wave resonator

Abstract

Embodiments provide a solidly-mounted bulk acoustic wave (BAW) resonator and method of making same. In embodiments, the BAW resonator may include a planzarization portion in an inactive region of the BAW resonator that is coplanar with a piezoelectric layer of the BAW resonator in an active region of the BAW restonator. Other embodiments may be described and claimed.

What is claimed is: 
     
       1. A bulk acoustic wave (BAW) resonator comprising:
 a border region that is located between an inactive region and an active region, the border region, the inactive region, and the active region intersecting a first axis; 
 a substrate in the inactive region, border region, and active region, the substrate to include silicon (Si), the substrate parallel to the first axis; 
 a mirror layer coupled with the substrate, the mirror layer disposed in the inactive region, border region, and active region and including a plurality of layers of Silicon Oxide (SiO2) and a plurality of layers of Tungsten (W); 
 a bottom electrode layer coupled with the mirror layer, the bottom electrode layer disposed in the border region and the active region and including a layer of Tungsten (W) and a layer of Aluminum-Copper (AlCu); 
 a piezoelectric layer coupled with the bottom electrode layer, the piezoelectric layer disposed in the border region and the active region and including Aluminum Nitride (AlN); 
 a top electrode layer coupled with the piezoelectric layer, the top electrode layer disposed in the border region and the active region and including a layer of Tungsten (W) and a layer of Aluminum-Copper (AlCu); and 
 a planarization layer coupled with the mirror layer, the planarization layer adjacent to the piezoelectric layer, the planarization layer and the piezoelectric layer intersecting the first axis, the planarization layer being disposed in the inactive region and including a planarization material. 
 
     
     
       2. The BAW resonator of  claim 1 , wherein the planarization material includes Silicon Oxide (SiO 2 ), Silicon Nitride (SiN), or Hafnium Oxide (HfO 2 ). 
     
     
       3. The BAW resonator of  claim 1 , further comprising a mass layer coupled with the top electrode layer in the border region. 
     
     
       4. The BAW resonator of  claim 1 , wherein the border region includes a portion of the piezoelectric layer, top electrode, bottom electrode layer, or mirror layer with reduced mass. 
     
     
       5. A bulk acoustic wave (BAW) resonator comprising:
 a piezoelectric layer that includes a piezoelectric material and vertically located between a first electrode and a second electrode in an active region and a border region of the BAW resonator; and 
 a planarization layer that includes a planarization material that is different than the piezoelectric material and is located horizontally adjacent to the piezoelectric layer in an inactive region of the BAW resonator that is horizontally adjacent to the border region of the BAW resonator, the planarization layer to improve suppression of spurious resonances of the BAW resonator. 
 
     
     
       6. The BAW resonator of  claim 5 , wherein the planarization material includes Silicon Oxide (SiO 2 ), Silicon Nitride (SiN), or Hafnium Oxide (HfO 2 ). 
     
     
       7. The BAW resonator of  claim 5 , wherein the piezoelectric material includes Aluminum Nitride (AlN). 
     
     
       8. The BAW resonator of  claim 5 , wherein the second electrode is a bottom electrode that is coupled with a mirror layer. 
     
     
       9. The BAW resonator of  claim 8 , wherein the mirror layer is a Bragg mirror layer. 
     
     
       10. The BAW resonator of  claim 8 , wherein the mirror layer includes one or more layers of a conductive material and one or more layers of a dielectric material. 
     
     
       11. The BAW resonator of  claim 5 , wherein the border region includes a mass layer coupled with the first electrode in the border region on a side of the first electrode opposite the piezoelectric layer. 
     
     
       12. The BAW resonator of  claim 5 , wherein the border region includes a portion of the piezoelectric layer, first electrode, second electrode, or mirror layer. 
     
     
       13. The BAW resonator of  claim 5 , wherein the first electrode or the second electrode include an Aluminum-Copper (AlCu) layer and a Tungsten (W) layer. 
     
     
       14. A bulk acoustic wave (BAW) resonator comprising:
 an active region that is coupled with and adjacent to a border region, the active region and the border region intersecting a first axis; 
 an inactive region that is coupled with and adjacent to the border region on a side of the border region opposite the active region; 
 a piezoelectric layer located between a top electrode and a bottom electrode, the piezoelectric layer, the top electrode, and the bottom electrode intersecting a second axis that is perpendicular to the first axis in the active region and the border region; 
 a mirror layer coupled with the piezoelectric layer, the mirror layer perpendicular to and intersecting the second axis; and 
 a planarization layer in the inactive region that is adjacent to and coupled with the piezoelectric layer, the planarization layer and the piezoelectric layer intersecting the first axis. 
 
     
     
       15. The BAW resonator of  claim 14 , wherein the mirror layer includes Silicon Oxide (SiO 2 ). 
     
     
       16. The BAW resonator of  claim 14 , wherein the mirror layer includes one or more layers of Silicon Oxide (SiO 2 ) and one or more layers of Tungsten (W). 
     
     
       17. The BAW resonator of  claim 14 , wherein the piezoelectric layer includes Aluminum Nitride (AlN). 
     
     
       18. The BAW resonator of  claim 14 , wherein the border region includes a mass layer coupled with the top electrode in the border region on a side of the top electrode opposite the piezoelectric layer. 
     
     
       19. The BAW resonator of  claim 14 , wherein the border region includes a portion of the piezoelectric layer, top electrode, bottom electrode, or mirror layer with reduced mass. 
     
     
       20. The BAW resonator of  claim 14 , wherein the top electrode or the bottom electrode include an Aluminum-Copper (AlCu) layer and a Tungsten (W) layer. 
     
     
       21. The BAW resonator of  claim 14 , wherein the planarization material includes Silicon Oxide (SiO 2 ), Silicon Nitride (SiN), or Hafnium Oxide (HfO 2 ).